Looks great. I guess this would be a great time to think of maybe trying your luck with Kickstarter (that is if you are interested in continuing working with such hardware). Either way a nice write up for a cool little project !
His BOM is just ~$60 off Sansaire's retail price, which is an integrated circulator with performance near Polyscience's. This is a bad idea for a Kickstarter: there is already an open price war between commercial-quality circulators. They'll be under $100 within the next couple years (it's just not that expensive to produce them.)